Cog-belt &amp; method for its production

ABSTRACT

An endless belt is described having a tensile-loaded elastomeric body supporting circumferentially spaced cogs or teeth. These cogs contain an embedded member extending transversely to the direction of rotation of the belt, in combination with an outer fabric layer positioned along the surface of the cogs. As a modification, the side of the belt opposite the toothed side may carry load transmitting elements for dual utilization of the same belt.

United States Patent [1'91 Redmond, Jr.

[ Nov.'20, 1973 COG-BELT & METHOD FOR ITS PRODUCTION [76] Inventor: John D. Redmond, Jr., Littleton,

[22] Filed: Oct.14, 1971 [21] Appl. No.: 189,440

[52] US. Cl 74/231 C [51] Int. Cl Fl6g 5/00, F16g 5/20 [58] Field of Search 74/231 C, 232, 237

[56] References Cited UNITED STATES PATENTS 2,182,461 12/1939 Yeakel 74/231 C 2,983,637 5/1961 Schmidt 74/231 C 3,349,634 10/1967 Terhune et a 74/231 C 3,297,514 1/1967 Poeschl et a1 74/232 X 2,189,049 2/1940 Ungar 74 233 FOREIGN PATENTS OR APPLICATIONS 1,191,971 4 1959 France ..74 231c Primary Examiner-Milton Kaufman Assistant ExaminerFrank H. McKenzie, Jr. Attorney Raymond Fink [57 ABSTRACT An endless belt is described having a tensile-loaded elastomeric body supporting circumferentially spaced cogs or teeth. These cogs contain an embedded member extending transversely to the direction of rotation of the belt, in combination with an outer fabric layer positioned along the surface of the cogs. As a modification, the side of the belt opposite the toothed side may carry load transmitting elements for dual utilization of the same belt.

25 Claims, 5 Drawing Figures PATENIEDNUVZOMS 3772.929 sum 10F 2 INVENTOR. JOHN REDMOND BY cwwewdagfi ATTORNEY PATENTEUHUV20 1975 3,772,929

SHEET 2 BF 2 WWW/' INVENTOR. JOHN REDMOND ATTORNEY l COG-BELT & METHOD FOR ITS PRODUCTION BACKGROUND OF THE INVENTION This invention relates to endless belts of the cog type containing a shear, abrasion and noise resistant cover element in combination with a transverse positioning member contained within the body portion of the cogs, and further relates to a method for producing such belts.

Positive drive or synchronous drive rubber transmission belts customarily are provided with an abrasion resistant or shear resistant fabric covering on the cog teeth, such as shown in U. S. Pat. No. 2,507,852. The methods for positioning the fabric along the tooth face have generally required special equipment or handling. With the protective fabric covering, the belt has an increased load life, although the cogs oftentimes do not possess the necessary shear resistance for prolonged life desired in many applications. A further drawback with prior art belts has been the lack of any suitable means, e,g, a transverse cog member, for proper alignment and support of the tensile members during operation of the belt. Without the provision of such a structural supporting means, the tensile members have had the tendency to displace non-uniformly in some instances so that the resultant relative position of the tensile members in the overcord is not exactly maintained.

It has been recognized that power transmission belts constructed of a castable elastomer, e.g., liquid polyurethane, offer a number of significant advantages over conventional rubber belting. Among these advantages are that the liquid cast belt is less susceptible to flex fatigue, may be driven around smaller sheaves, and has overall improved load life. These cast belts may also be vacuum spin cast in a single operation as contrasted to the numerous steps required to build a conventional rubber tooth-type belt. To the best knowledge of applicant, no cast elastomer cog-type belt has been produced commercially which includes the protective fabric covering about the teeth or cogs of the belt, due apparently to the lack of an economical method of applying such a fabric layer. Without such a layer, the cogs of the belt are susceptible to damaging shearing forces, and, because of the exposure of polyurethane or other elastomer to sheave surfaces, noticeable and objectionable noise is produced.

Typical prior art references relating to the general field of the present invention include U. S. Pat. Nos. 1,890,080 (Freedlander), 2,507,852 (Case), 2,514,429 (Waugh), 3,078,206 (Skura), 3,138,962 (I-Iaines et al.), 3,200,180 (Russ et al.) and 3,580,767 (Barnes et al).

It is a primary object of the present invention to overcome the drawbacks of the prior art and provide a power transmission belt of the direct or synchronous drive type having improved load life and composed of a rubber-like castable or noncastable material.

It is a further object of the invention to provide a method for producing a liquid castable cog-type transmission belt having in combination a transverse member in the cog, and a wear resistant fabric layer substantially at the surface of the cog.

It is still another object to have such a transverse cog member in combination with an outer fabric layer as utilized in a cast polyurethane belt.

SUMMARY OF THE INVENTION,

Briefly described, in one aspect of the invention, an endless belt is provided having an elastomeric body portion with longitudinal tensile members embedded in the overcord of the body, and a plurality of spaced cogs intimately bonded with the overcord and containing transverse members embedded within the cog and in close proximity to the tensile members. The inner circumferential face of the belt formed by alternating cog and land portions carries a layer of reinforcing fabric intimately bonded to the elastomeric body section. As a modification of the aforementioned structure, the overcord portion of the belt opposite the inner facial cog portions may be provided with one or more load transmitting elements, e.g., circumferentially extending V- or trapezoidal elements.

In another aspect of the invention, a method for casting cog-type power transmission belts from flowable elastomeric materials is described, including the steps of: (1) forming a mold cavity defined by a mold mandrel and an outer mold shell, one of which has a plurality of axial notches; (2) wrapping an extensible fabric about the surface of the notched mold portion; (3) placing preferably fibrous loading members upon the extensible fabric and superimposed over the axial notches; and (4) forcing the fibrous loading members and extensible fabric into the bottom contour of the notches; and (5) introducing a substantially liquid elastomeric material into the mold cavity and polymerizing the elastomeric form in the mold to produce a sleeve containing one or more unitary endless cog-type belts.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more readily understood by reference to the accompanying drawings, in which like numerals designate like parts in the several figures, and wherein:

FIG. 1 is a fragmentary, perspective view of one preferred power transmission. belt made according to the invention;

FIG. 2 is one type of casting assembly for carrying out the method of casting according to the invention;

FIG. 3 is a fragmentary, perspective view of a molding apparatus for producing a combination cog and multiple V power transmission belt according to the invention;

FIG. 4 is a cross-sectional view taken along a land portion of a belt sleeve made in the apparatus shown in FIG. 3. I

FIG. 5 is a longitudinal cross-sectional fragmentary view of another embodiment of the invention.

PREFERRED EMBODIMENTS OF THE INVENTION Referring to FIG. 1 an endless cog-type belt is shown. The belt consists of an overcord section 12 of an elastomeric material and a series of spaced cogs or teeth 16,

also containing an elastomeric material 14. The elastothanes, polybutadiene, polyisoprene or blends of these materials with each other or with natural rubber. The elastomer overcord 12 is preferably loaded with a reinforcing tensile layer or plurality of tensile members such as the longitudinally extending and spaced tensile cords 18. These tensile members 18 may consist of one or more strands of a conventional stress-resistant material such as polyamide cord, fiber glass, polyester cord or wire filaments. The tensile members may be prestressed or impregnated with a suitable material if desired.

According to the invention, the cogs or teeth 16 of the belt take on a particular configuration. Specifically, the teeth are characterized by containing one or more embedded transverse members 20 and in combination therewith, an inner-peripheral contour-following fabric layer 22.

The reinforcing fabric 22 intimately fits along the inner-periphery of the belt forming a face cover for the cog teeth 16 and alternating land portions 24. This fabric may be of a conventional weave, consisting of warp and weft threads at any desired angle, or may consist of warp threads held together by spaced pic cords among other configurations. If desired, the fabric may be cut on a bias as shown. Conventional fabrics may be employed, such as cotton, polyester, polyamide, hemp, jute and various other natural and synthetic fibers. The fabric may be rubberized if desired. In a preferred embodiment of the invention, when utilizing a liquid castable elastomer such as polyurethane, the fabric layer 22 preferably consists of an expansible wear-resistant fabric such as nylon. When utilizing readily flowable elastomers such as polyurethane, the fabric layer 22 will usually be impregnated with the elastomer and have an outer skim-coating of the elastomer which forms the inner face of the belt (not shown).

The wear-resistant layer 22 performs a number of functions, including providing the cogs 16 with a resistance to shear and abrasive forces commonly encountered, and forms a protective layer shielding both the tensile members 18 along the land portions 24 of the inner face of the belt as well as protecting the transverse cog members 20 from exposure to shear and abrasion. With respect to elastomers which have a tendency to generate noise when the cogs of the belt engage the cooperating gear teeth of a sheave, e.g., some urethane polymers, the resistant fabric layer 22 operates to isolate the elastomer body, such as portion 14 from direct contact with the sheaves. While urethane elastomers offer a number of advantages over conventional elastomers in positive drive belts, the noise generation exhibited by urethane belts has presented a significant objection to their use heretofore.

The transverse members 20 embedded in the cogs perform a number of important functions. In one aspect, these transverse members increase the shear strength of the cogs and tend to dampen noise produced when the cogs strike the cooperating gear teeth surfaces of the driving and driven sprockets or sheaves. It is preferred that this transverse member substantially fill the cog portion vertically, so as to come into contact or in close proximity to both the fabric member 22 and tensile section 18. Such positioning provides a reinforcement or support for the fabric layer 22 and maintains the tensile section 18 in relative alignment, e.g., substantially preventing the individual tensile cord members 18 from being displaced with respect to each other. The transverse members 20 additionally lend transverse rigidity to the belt, inhibiting undesirable waves or undulations along the face of the belt during operation. The transverse members also help position the fabric layer down in the grooves of the mandrel during the building process. In general, the belt may be built up on a conventional drum, and subjected to transfer, compression, injection or other type of molding or casting operation. In a preferred form of the invention, when utilizing a fiowable elastomer, the transverse members 20 serve the very important aforementioned function of positioning the fabric along the intercontour of the belt during casting.

The transverse member 20 may consist of one or more members extending generally transverse to the direction of rotation of the belt. The transverse members may be formed of any suitable elongated member of any suitable cross-sectional shape preferably acting to reinforce the cog. Examples of suitable materials include polyesters, cellulosic materials such as rayon, and cotton, polyamides such as nylon, hard rubbers, wire, or fiber glass, or other materials present in various configurations exemplified by cords, filaments, twisted strands rope, tubes, braided fibers, rods, etc. If the cross member 20 is not naturally adherent to the elastomeric body 14 and 12, the cross member 20 may be suitably impregnated with a composition which will effect the necessary adherence.

A modification of the belt of FIG. 1 is shown in FIG. 5 in cross-section taken along the direction of travel of the belt. The belt consists of the usual elastomeric overcord section 52 containing a circumferentially extending tensile layer 54. The undercord of the belt carries a plurality of spaced teeth or cogs 56, which, according to the invention, have an outer wear and abrasion resistant fabric outer layer 22 and a plurality of transverse members 20. These transverse members fill a major proportion of the cogs S6 and particularly the vertical distance a between the tensile member and innermost portion of the cogs. This gun belt configuration has a deep notch between cogs, and preferably the ratio of a:b, 17 being the distance between adjacent cogs measured at their respective bases, is at least about 1.0:1, and more preferably at least 1.411. This belt has a high load carrying capacity and in many instances may transmit power previously restricted to chain type drives.

The elastomeric overcord layer 12 (or 52) of the belt may carry positive drive elements such as cogs or teeth of various shapes, or alternatively may carry a power transmitting portion, such as one or more V-sections. The latter configuration is shown in FIG. 4 of the drawings, a view looking along the direction of travel of the belt and taken sectionally along one of the land portions between successive cogs 16. The side of the belt opposite the tooth portion 16 comprises a plurality of spaced longitudinally extending V-elements tied together by a common elastomeric tie-band section 26, containing circumferentially extending tensile cord 18. Additional tensile layers or additional'transverse reinforcing layers may be utilized in the multiple V and/or tie-band sections for increased rigidity and resistance to elongation and deformation. Between the V or trapezoidal elements 28 there is preferably a vertical flat portion 30 in order to provide the necessary degree of clearance between the land of the sheave and the bottom of the tie-band 26 during belt operation so that the modulus of the tie-band alone is not depended upon to provide relative freedom between the V-portions 28 to accommodate inaccuracies of the sheave. Furthermore, this clearance provided by the vertical flat portion allows foreign elements such as rocks and cinders to lodge themselves between the land of the sheave and the bottom of the tie-band, and prevent disengagement of the belt during operation. Furthermore, this vertical clearance 30 allows the individual V-portions 28 to accommodate their own wedging action in the individual grooves of the sheaves with which they co-act, increasing power transmission capability.

A preferred general technique for producing belts of the aforementioned type, and particularly directed to producing such belts cast from liquid elastomers, is described in U. S. Pat. Nos. 3,138,962 (Haines, et al.) and 3,200,180 (Russ, et al.). Accordingly, as is shown in FIG. 2, a casting assembly 32 broadly comprises an outer vacuum chamber 34, a platform 36 upon which the vacuum chamber rests, a central rotatable shaft 38 extending from the outside of the vacuum chamber through the platform into the chamber upon which is supported an interior mandrel 40, and an outer-spaced concentric mold shell 42. The vacuum chamber 34 may be evacuated by an exhaust line 44, which is connected to a vacuum pump (not shown). The liquid casting material is introduced by means of an entry port 46 which is directed toward the top of a distributing plate 48. As

the assembly is rotated, the liquid elastomer is forced' to the outer regions by means of centrifugal force and by means of a baffle system and guide system incorporated as part of the distributing plate 48. On the outer region of the plate, the material is then directed to the cavity 41 bounded by the central mandrel 40 and the outer mold shell 42.

This type of centrifugal casting lends itself to a number of modifications. Thus, a laminated belt structure having different density materials may be manufactured by metering together two or more components having different specific gravities and utilizing the centrifugal force created by the rotating mandrel to separate components, the heavier gravity component being forced to the outer part of the mold, and the lighter gravity component forced toward the center of the mold, etc. Furthermore, one could partially fill the outer extremity of the mold volume with one component followed by a partial curing step, and further followed by metering in a different component to form the inner portion of the mold and curing.

Various types of materials are available which may be cast. Examples are curable liquid elastomers exemplified by plastisols, organosols, liquid chloroprenes,

liquid polysulfides, liquid rubbers, silicones, epoxides,

urethanes, carboxylated butadiene-acrylonitrile, polyester based resins, polyether based resins, together with others. Polyurethane elastomers are generally preferred at present because of their tensile strength, abrasion resistance and satisfactory modulous and elasticity character. In a conventional manner, a polyurethane prepolymer (formed by reaction of an active hydrogencontaining compound with a polyisocyanate) having a certain free NCO content is compounded with a curing agent and an amount of plasticizer or other ingredient, if desired, and introduced into the mold cavity.

Conventional curing agents may be utilized, such as organo nitrogen-containing compounds exemplified by substituted aromatic amines.

Referring particularly to FIG. 3, there is shown a mold cavity for casting a belt of the type shown in cross-section in FIG. 4. A trapezoidally notched mold shell 42 concentrically surrounds an inwardly disposed mandrel 40 having spaced axially extending notches 45 and alternating upstanding portions 47. At the top and bottom of the mandrel are a pair of end cap closures 50 having a plurality of notches 49 lining up with the mandrel notches 45. I

According to a preferred embodiment of the method of present invention, the notched end caps 50 are placed in position and a layer of fabric 22 is wrapped about the lubricated mandrel 40. This fabric is preferably of an extensible nature, allowing it to be readily stretched and conformed to the mandrel notches 45. The transverse members 20 are then woven in an upand-down manner through adjacent notches of one end cap and then through alternate notches of the opposite end cap, until the entire mandrel is woven. In the succeeding step, the tensile member 18 is spirally wound about the circumference of the mandrel and under such tension as to force the transverse members 20 against the fabric layer 22, forcing the latter into conformity with the notches 45 of the mandrel. Preferably, the geometry of the mandrel notches 45 is chosen to accommodate substantially the entire cross-section of the transverse cog members(s) 20.

Once the tensile members 18 have been wrapped about the mandrel, the transverse members 20 may be cut at a point just below the end caps, and the resultant wrapped mandrel placed in a mold of the type shown in FIG. 2, for instance, ready for the casting operation. Centrifugal casting combined with applied vacuum may be employed for good results. Such a casting method is described in the above-mentioned l-laines et a1 and Russ et al patents.

After polymerization has taken place and sufficient cure time allowed, the mold may be disassembled and the resultant sleeve of belts cut into individual belts of desired width. A skiving operation may be employed to give the desired final configuration to the teeth and/or trapezoidal element portions. Thus, skiving could provide the sole method for notching the overcord (opposite the cog side) into desired V-forms, if desired.

It should be understood that the invention is capable of a variety of modifications and variations which will become apparent to those skilled in the art upon a reading of this specification. Such modifications and variations and equivalents are intended to become a portion of the invention and fall within the scope of the appended claims. For instance, while the method of the present invention has been directed primarily to casting of liquid elastomeric material utilizing a notched mold mandrel and an outer mold sleeve, the parts could be reversed so as to mold the belt in the reverse manner and then subsequently flip the belt to achieve the desired orientation. Furthermore, the particular method of weaving the transverse positioning members about the end caps for positioning the fabric layer 22 at the inner surface of the belt is merely illustrative of a number of suitable methods for accomplishing the same result, and is not meant to limit the invention to such disclosed method.

What is claimed is:

1. An endless power transmission belt comprising:

a. a body portion composed of an elastomeric material;

b. a fibrous tensile layer disposed longitudinally within said body section and forming a bond therewith;

c. a plurality of spaced teeth bonded with and disposed along the inner periphery of said body portion to form alternating teeth and land portions, the teeth containing loading material oriented substantially transversely to the direction of travel of the belt, and embedded within an elastomeric material; and

d. a layer of wear resistant fabric positioned substantially along the periphery of said alternating land and teeth portions of the belt.

2. The transmission belt of claim 1 wherein said fibrous tensile layer is composed of a plurality of spaced strain resisting prestressed cords.

3. The transmission belt of claim 1 wherein the body portion has an outer peripheral portion carrying at least one power transmitting longitudinally extending element.

4. The transmission belt of claim 3 wherein the power transmitting elements consist of a plurality of closely spaced V-elements held together by a tie-band support provided by the body portion of the belt.

5. The transmission belt of claim 4 wherein the base of the V-elements formed at the intersection with the tie-band contain vertical flat portions, whereby engagement of the V-element portion of the belt with a cooperating sheave leaves a space between the sheave and tie-band.

6. The transmission belt of claim 1 wherein the transversely extending loading material consists of at least one reinforcing cord, the loading material substantially filling the vertical space between the fibrous tensile layer and the wear resistant fabric layer along the innermost portion of the teeth.

7. The transmission belt of claim 1 wherein the fabric layer consists of a woven highly extensible fabric.

8. The transmission belt of claim 7 wherein the fabric consists of polyamide fibers.

9. The transmission belt of claim 1 wherein the elastomeric materials forming said body portion and forming a portion of said teeth respectively, are formed of the same material.

10. The transmission belt of claim 9 wherein the elastomeric material is formed from a flowable rubber-like material.

11. The transmission belt of claim 10 wherein said rubber-like material is liquid castable polyurethane.

12. The transmission belt of claim 1 wherein the ratio of the height of an individual tooth, measured from the tensile member to the innermost portion of the tooth, to the distance between successive teeth, measured at their respective bases, is at least 1.0:1.

13. The transmission belt of claim 12 wherein said ratio is at least 1.4:1.

14. The transmission belt of claim 1 wherein the transversely oriented loading material fills a major proportion of the cross-section of said teeth.

15. The transmission belt of claim 1 wherein the transversely oriented loading material is in contact with said fibrous tensile layer thereby providing alignment support thereto.

16. The transmission belt of claim 1 wherein said teeth have an innermost face portion and wherein at least a portion of the transversely oriented loading material is in contact with said innermost face portion.

17. The transmission belt of claim 1 wherein substantially the entire longitudinal cross-section of the teeth accommodates said transversely oriented loading material.

18. The transmission belt of claim 1 wherein the transversely oriented loading material is in close proximity to said fibrous tensile layer thereby providing alignment support therefor.

19. The transmission belt of claim 1 wherein said teeth have an innermost face portion and wherein at least a portion of the transversely oriented loading material is in close proximity to said innermost face portion.

20. A cast polyurethane cog-type power transmission belt comprising:

a polyurethane body section;

a tensile section disposed longitudinally within said body section and forming a bond therewith;

a plurality of spaced cogs integral with said body section and disposed along the inner periphery thereof to form alternating teeth and land portions, said teeth having an innermost face portion;

loading material embedded within said teeth and oriented substantially transversely to the direction of travel of the belt;

said loading material filling a major proportion of the cross-section of said teeth; and

wear resistant fabric positioned along the inner periphery of said land and teeth portions including said innermost face portion of the teeth.

21. The belt of claim 20 wherein said tensile section comprises fibrous tensile members, said transversely oriented loading material contacting said fibrous tensile members to provide aligning support therefor.

22. The belt of claim 20 wherein at least a portion of the transversely oriented loading material is in contact with the innermost face portion of the teeth carrying said wear resistant fabric.

23. The belt of claim 20 wherein the transversely oriented loading material substantially fills the space extending between said tensile section and the wear resistant fabric positioned along the innermost face portion of the teeth.

24. The belt of claim 20 wherein said tensile section comprises fibrous tensile members, said transversely oriented loading material coming into close proximity to said fibrous tensile members to provide aligning support therefor.

25. The belt of claim 20 wherein at least a portion of the transversely oriented loading material is in close proximity to the innermost face portion of the teeth carrying said wear resistant fabric. i

FORM PO-105O (10-69) UNITED STATES PATENT OFFICE QETIFICATE OF CORRECTION Patent 3,772,929 Dated November 2L 1973 lnventofls) John D. Redmond, Jr.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Title of invention, should read :1 POSITIVE DRIVE BELT AND METHOD FOR ITS PRODUCTION Signed and Sealed this second Day Of September 1975 [SEAL] AIIQSI.

C. MARSHALL DANN (mnmmimu'r ufluIUHIS and Trademarks RUTH C. MASON Arlesling Officer USCOMM-DC 60376-P69 U.S, GOVERNMENT PRINTING OFFICE 1 "869- 9 0 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No; 5,772,929 .Issued' November 20, 1973 I John D. Redmond, Jr.

It is certified that error appears in the aboveidentified patent and that said Letters Patent is hereby corrected as shown below: I

The assignee of this patent should be shown as The Gates Rubber Company.- v

' Signed and sealed this 7th day of May 197E.

(SEAL) Attest:

EDWARD l-i.E-LETCHER,JR. C. f-IARSHALL DANN Attesting Officer Commissioner of Patents 

1. An endless power transmission belt comprising: a. a body portion composed of an elastomeric material; b. a fibrous tensile layer disposed longitudinally within said body section and forming a bond therewith; c. a plurality of spaced teeth bonded with and disposed along the inner periphery of said body portion to form alternating teeth and land portions, the teeth containing loading material oriented substantially transversely to the direction of travel of the belt, and embedded within an elastomeric material; and d. a layer of wear resistant fabric positioned substantially along the periphery of said alternating land and teeth portions of the belt.
 2. The transmission belt of claim 1 wherein said fibrous tensile layer is composed of a plurality of spaced strain resisting prestressed cords.
 3. The transmission belt of claim 1 wherein the body portion has an outer peripheral portion carrying at least one power transmitting longitudinally extending element.
 4. The transmission belt of claim 3 wherein the power transmitting elements consist of a plurality of closely spaced V-elements held together by a tie-band support provided by the body portion of the belt.
 5. The transmission belt of claim 4 wherein the base of the V-elements formed at the intersection with the tie-band contain vertical flat portions, whereby engagement of the V-element portion of the belt with a cooperating sheave leaves a space between the sheave and tie-band.
 6. The transmission belt of claim 1 wherein the transversely extending loading material consists of at least one reinforcing cord, the loading material substantially filling the vertical space between the fibrous tensile layer and the wear resistant fabric layer along the innermost portion of the teeth.
 7. The transmission belt of claim 1 wherein the fabric layer consists of a woven highly extensible fabric.
 8. The transmission belt of claim 7 wherein the fabric consists of polyamide fibers.
 9. The transmission belt of claim 1 wherein the elastomeric materials forming said body portion and forming a portion of said teeth respectively, are formed of the same material.
 10. The transmission belt of claim 9 wherein the elastomeric material is formed from a flowable rubber-like material.
 11. The transmission belt of claim 10 wherein said rubber-like material is liquid castable polyurethane.
 12. The transmission belt of claim 1 wherein the ratio of the height of an individual tooth, measured from the tensile member to the innermost portion of the tooth, to the distance between successive teeth, measured at their respective bases, is at least 1.0:1.
 13. The transmission belt of claim 12 wherein said ratio is at least 1.4:1.
 14. The transmission belt of claim 1 wherein the transversely oriented loading material fills a major proportion of the cross-section of said teeth.
 15. The transmission belt of claim 1 wherein the transversely oriented loading material is in contact with said fibrous tensile layer thereby providing alignment support thereto.
 16. The transmission belt of claim 1 wherein said teeth have an innermost face portion and wherein at least a portion of the transversely oriented loading material is in contact with said innermost face portion.
 17. The transmission belt of claim 1 wherein substantially the entire longitudinal cross-section of the teeth accommodates said transversely oriented loading material.
 18. The transmission belt of claim 1 wherein the transversely oriented loading material is in close proximity to said fibrous tensile layer thereby providing alignment support therefor.
 19. The transmission belt of claim 1 wherein said teeth have an innermost face portion and wherein at least a portion of the transversely oriented loading material is in close proximity to said innermost face portion.
 20. A cast polyurethane cog-type power transmission belt comprising: a polyurethane body section; a tensile section disposed longitudinally within said body section and forming a bond therewith; a plurality of spaced cogs integral with said body section and disposed along the inner periphery thereof to form alternating teeth and land portions, said teeth having an innermost face portion; loading material embedded within said teeth and oriented substantially transversely to the direction of travel of the belt; said loading material filling a major proportion of the cross-section of said teeth; and wear resistant fabric positioned along the inner periphery of said land and teeth portions including said innermost face portion of the teeth.
 21. The belt of claim 20 wherein said tensile section comprises fibrous tensile members, said transversely oriented loading material contacting said fibrous tensile members to provide aligning support therefor.
 22. The belt of claim 20 wherein at least a portion of the transversely oriented loading material is in contact with the innermost face portion of the teeth carrying said wear resistant fabric.
 23. The belt of claim 20 wherein the transversely oriented loading material substantially fills the space extending between said tensile section and the wear resistant fabric positioned along the innermost face portion of the teeth.
 24. The belt of claim 20 wherein said tensile section comprises fibrous tensile members, said transversely oriented loading material coming into close proximity to said fibrous tensile members to provide aligning support therefor.
 25. The belt of claim 20 wherein at least a portion of the transversely oriented loading material is in close proximity to the innermost face portion of the teeth carrying said wear resistant fabric. 